Detection of such events as a result of EAS fluctuations is unlikely (\(\lesssim 10^{-10}\) ) [1]}, [2]}, [3]}. So, this phenomenon was originally interpreted as a result of coplanar generation of fragmentation-region MEPs \((x_{ Lab} = E/E_0 \gtrsim 0.01)\)  in first interactions of primary protons characterized by MEPs' high transverse momenta (\(p_{t}^{\, copl} \gtrsim 1\)  GeV/c) forming a coplanarity plane.
